What Is Energy Efficiency?
2 min read
Your washing machine, electric bulbs and heating can have varying levels of . The energy efficiency of a machine or system is the relationship between the useful energy given out and the energy consumed.
What Is ?
When one form of energy is converted into another, some of the energy initially available is dissipated.
Example for a washing machine:
It consumes a certain amount of electrical energy = energy consumed.
Some of this energy is converted into = useful energy.
The rest is lost as = energy lost.
The efficiency of this washing machine = the relationship between the useful energy and the energy consumed by the machine.
Calculating it as a % is simple: Efficiency (η) = (Eout)/(Ein) x 100
η: Efficiency
Eout: Useful energy
Ein: Energy consumed
Example: The efficiency of an incandescent light bulb is around 5%. This means only 5% of the energy consumed by the bulb is converted into useful energy, i.e., producing light. 95% of the energy consumed is lost as heat.
The efficiency of an LED lamp is more than 30%. It is therefore more efficient, because less energy is lost. Efficiency is key data for calculating energy performance.
Energy performance = average energy efficiency of a system (e.g., a building).
To assess this, we must calculate the average of several representative efficiency readings (heating, insulation, air conditioning, lighting).
Summary:
- The efficiency of a device or system = the relationship between the useful energy given out and the energy consumed.
- Energy consumed = total amount of energy consumed by the device.
- Useful energy = proportion of energy consumed for the desired purpose.
- Efficiency is key data for calculating energy performance (e.g., of a building).
Energy Sufficiency and Efficiency
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